EFFECTS OF CENTRIFUGATION AND SPECIMEN PREPARATION TECHNIQUE ON BRONCHOALVEOLAR LAVAGE ANALYSIS IN HORSES

Bronchoalveolar lavages (BAL) were performed for 6 healthy horses and 8 horses with lower airway diseases (LAD). Total cell and differential counts were performed before and after centrifugation and resuspensio n of the BAL cells in a small volume of fluid; there was no difference in the total cell counts, but mast cell percentages were significantl y (P<0.05) lower, after centrifugation, in the LAD group. The two spec imen preparation techniques compared were cytocentrifugation and centr ifugation on microscope glass covers. For both groups of horses, lymph ocyte percentages were significantly lower on cytocentrifuged specimen s; there was also an increase in the other predominant cell type, i.e. macrophages in healthy horses and neutrophils in horses with LAD. Lym phocyte percentages in healthy horses were higher than those reported in previous studies, possibly because of a long-standing exposure to a high-dust environment. This study suggests that one centrifugation of the BAL fluid does not affect total cell counts, but may cause a decr ease in mast cell percentage; cytocentrifugation is associated with a consistent decrease in lymphocyte percentage.